SOURCE

function add(...args) { //这是需要处理的函数，任意
return args.reduce((pre, cur) => {
  return pre + cur;
});
}


const memorize = (fn) => { //处理函数
let map = new Map();
return function (...args) {
  let keys = Array.from(map.keys());
  console.log(keys);
  let is = false;
  for (let item of keys) {
    is = args.every((val, index) =>{
      return val === item[index]
    });
    if (is) {
      console.log('使用缓存')
      return map.get(item)
    }
  }
  console.log('重新计算')
  let r = fn(...args);
  map.set(args, r);
  return r;
}
}
const f = memorize(add); //调用
console.log(f(1, 2));
console.log(f(3, 4));
console.log(f(3, 4));
console.log(f(1, 2));
console.log(f(1, 2, 3));
console.log(f(1, 2, 4));
console.log(f(5, 6));
console.log(f(1, 2, 3));


//实现一个函数只能通过new调用，通过普通方式调用时抛出错误,并且每次返回的对象里的id属性要递增，不能使用全局变量

const dog = (function (){
  let id = 0;
  return function(){
    	if(!new.target){
        	throw new Error('new only');
      }
    	this.id = ++ id;
  }
})();
console.log(new dog());
console.log(new dog());
console.log(new dog());

let a = 123123234.123;
let b = "123,123,234.123";

function change(str){
    let arr = str + '';
    arr = arr.split('.');
    let re = arr[0].split('').reverse();
    let stack = [];
    let count = 0;
    for(let i=0;i<re.length;i++){
        stack.push(re[i]);
        count++;
        if(count == 3 && i<re.length-1){
            stack.push(',');
            count = 0;
        }
    }
    return stack.reverse().join('') + '.' + arr[1];
}

console.log(change(a))

function f(arr){
	if(arr.length<1){
		return arr;
	}
	let mid = arr[Math.floor(arr.length/2)];
	let left = [],righ = [];
	arr.forEach(item => (item<mid?left:right).push(item));
	return [...f(left),mid,...f(right)];
}

let rotate = (matrix) =>{
    for(let i = 0; i < matrix.length; i++){
        for (let j = i; j < matrix[i].length; j++){
            [matrix[i][j],matrix[j][i]] = [matrix[j][i],matrix[i][j]]
        }
    }
    matrix.forEach(row=> row.reverse())
};

[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],

[
  [1,4,7],
  [2,5,8],
  [3,6,9]
]

//原地旋转输入矩阵，使其变为:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]